FIELD OF THE INVENTION
Unsaturated polyester resins are widely employed commercially in a variety of reinforced fabrication systems including among others matched metal-die compression, transfer, pultrusion and injection molding. These systems involve curing a formulated compound at high temperatures and pressures in hardened and chrome plated molds. These methods provide the highest volume and highest part uniformity of any thermoset molding technique.
For the purposes of the descriptions dealt with herein, these resins are characterized in terms of systems containing them, and the systems encompass the following types:
1. Resin systems free of reinforcement. This is a resin system utilizes a thermosettable resin that is designed to be used as such or with reinforcement at the high temperatures and pressures utilized in a variety of reinforced fabrication systems including among others matched metal-die compression, transfer, pultrusion and injection molding. When the term "resin system" is used herein, such contemplates a composition using a thermosettable resin that is free of reinforcement, fibrous or non-fibrous, unless it is specifically indicated to contain reinforcement as contemplated in the definitions which follow.
2. "Reinforced resin system" is a resin system in which there is provided a sufficient amount of one or more of fibrous or non-fibrous materials as reinforcing agents that make a positive contribution to the physical properties of the molded product derived from the reinforced resin system.
3. "Non-fiber reinforced resin" system is a resin system in which there is provided a sufficient amount of one or more non-fibrous materials as reinforcing agents that make a positive contribution to the physical properties of the molded product derived from the non-fiber reinforced resin system. A non-fiber reinforced resin system is free of reinforcing amounts of a fiber.
4. "Fiber reinforced resin system" is a resin system in which there is provided a sufficient amount of one or more fibers as reinforcing agents that make a positive contribution to the physical properties of the molded product derived from the fiber reinforced resin system. A fiber reinforced resin system contemplates the optional presence of non-fiber reinforcing agent(s).
In order to minimize confusion in the descriptions which follow, the following terms as used in this specification and in the claims hereof, have the definitions set out for them:
The term "highly reactive olefinically unsaturated compound" means a olefinically polymerizable compound capable of providing crosslinking in the curing of a resin system containing the same, and having the following formula: EQU R--A PA1 wherein R is a functional olefinically unsaturated group which provides a reactivity rate (r.sub.1) [as defined in U.S. Pat. No.4,374,215] for the compound that is equal to or less than styrene, A is a moiety having the structure EQU X(R').sub.n PA1 wherein X is an organic group covalently bonded to R and R', R' is a functional olefinically unsaturated group which provides a reactivity rate (r.sub.1) [as defined in U.S. Pat. No. 4,374,215] for the compound that is equal to or less than styrene, and n is 0, 1, 2 or 3, provided that when X has less than 6 carbon atoms, n is 1, 2 or 3, and when X has at least 6 carbon atoms, n may be 0, 1, 2 or 3, and when n is 0, R provides a reactivity rate less than that styrene. PA1 The term "acrylyl crosslinkable monomer" means a highly reactive olefinically unsaturated compound that contains at least two acryl or methacryl groups per molecule or one acryl or methacryl group attached to a moiety containing at least 6 carbon atoms. PA1 The term "base resin system" means a resin system containing as essential components PA1 "low profile additive resin system" or "LPA resin system" means a resin system containing as essential components PA1 "resin system of the invention" means a low profile additive resin system to which has been added a highly reactive olefinically unsaturated compound. PA1 1. U.S. Pat. No. 4,525,498, issued Jun. 25, 1985, to Kenneth E. Atkins et al, describes an improved low profile additive composition suitable for use in molding application which contains a thermosetting unsaturated polyester, a thermoplastic polymer additive to control shrinkage and an ethylenically unsaturated monomer, by the addition of an epoxy compound that is essentially free of reactive unsaturation. PA1 2. U.S. Pat. No. 4,374,215 issued Feb. 15, 1983, to Kenneth E. Atkins, describes a polyester molding composition which is unique in the combination of a polyester resin, a copolymerizable olefinically unsaturated monomer, a thermoplastic polymer low profile additive to control shrinkage, and an effective amount of a second crosslinkable vinyl monomer having a reactivity ratio (r.sub.1) with styrene of greater than 1. PA1 3. U.S. Pat. No. 4,673,706 issued Jun. 16, 1987, to Kenneth E. Atkins, describes the addition of crosslinkable vinyl monomers and epoxy compounds to low shrinking polyester molding compositions containing unsaturated polyesters results in moldings with improved surface characteristics. PA1 4. U.S. Pat. No. 4,755,557, issued Jul. 5, 1988, to Kenneth E. Atkins et al, describes a molding composition containing an unsaturated polyester resin, a copolymerizable ethylenically unsaturated monomer, a thermoplastic low profile additive and a lactone monomer. PA1 5. U.S. Pat. No. 4,535,110 uses an isocyanate terminated urethane prepolymer composition in combination with thermoplastic low profile additives to yield improved shrinkage control of polyester molding compositions. PA1 i. a thermosetting unsaturated polyester resin, PA1 ii. an olefinically unsaturated monomer that is copolymerizable with the polyester resin, PA1 iii. a low profile additive for shrinkage control, and PA1 iv. one or more highly reactive olefinically unsaturated compounds in which highly reactive olefinically unsaturated compound(s) is present in the composition in an amount sufficient to improve the cracking resistance of the curable composition without adversely affecting the surface smoothness of the cured composition thereof. PA1 i. a thermosetting unsaturated polyester resin, PA1 ii. an olefinically unsaturated monomer that is copolymerizable with the polyester resin, PA1 iii. a low profile additive for shrinkage control, and PA1 iv. an acrylyl crosslinkable monomer present in the composition in an amount sufficient to improve the cracking resistance of the curable composition without adversely affecting the surface smoothness of the cured composition thereof. PA1 i. about 25 to about 70 weight percent of a thermosetting unsaturated polyester resin, PA1 ii. 25 to 70 weight percent of an olefinically unsaturated monomer that is copolymerizable with the polyester resin, PA1 iii. about 5 to about 25 weight percent of a low profile additive, and PA1 iv. about 1 to about 10 weight percent of a highly reactive olefinically unsaturated compound. PA1 i. about 25 to about 70 weight percent of a thermosetting unsaturated polyester resin, PA1 ii. 25 to 70 weight percent of an olefinically unsaturated monomer that is copolymerizable with the polyester resin, PA1 iii. about 5 to about 25 weight percent of a low profile additive, and PA1 iv. about 1 to about 10 weight percent of a an acrylyl crosslinkable monomer. PA1 i. about 10 to about 70 weight percent of a thermosetting unsaturated polyester resin, PA1 ii. about 5 to about 70 weight percent of an olefinically unsaturated monomer that is copolymerizable with the polyester resin, PA1 iii. about 2.5 to about 25 weight percent of a low profile additive, PA1 iv. about 5 to about 60 weight percent of fiber reinforcement, and PA1 v. about 0.5 to about 10 weight percent of a highly reactive olefinically unsaturated compound. PA1 a. a LPA resin system in which the polyester resin comprises the reaction product of an olefinically unsaturated dicarboxylic acid or anhydride with a polyol, in which no more than about 30 molar percent of the unsaturated acid or anhydride can be replaced with a non-crosslinkable acid; PA1 b. one or more of an epoxy monomer essentially free of reactive unsaturation and a secondary crosslinking monomer with an r.sub.1 value greater than 1 relative to styrene; and PA1 c. a highly reactive olefinically unsaturated compound which is present in amounts of 1-20 parts based on a total of 100 parts of the LPA resin system plus component b. above. PA1 i. a LPA resin system; PA1 ii. one or more highly reactive olefinically unsaturated compounds in which highly reactive olefinically unsaturated compound(s) is present in the composition in an amount sufficient to improve the cracking resistance of the curable composition without adversely affecting the surface smoothness of the cured composition thereof; PA1 iii. the optional presence of one or more of an epoxy monomer essentially free of reactive unsaturation and a secondary crosslinking monomer with an r.sub.1 value greater than 1 relative to styrene; and PA1 iv. an isocyanate terminated prepolymer material based either on polyether or polyester polyols. PA1 1. A distinct property improvement to the resin system and cured molded parts made therefrom is evident; PA1 2. A minor component in terms of concentration, such as the highly reactive olefinically unsaturated compounds, that makes a contribution to properties would by such fact be different in its performance from that of the major component(s), such as the crosslinkable monomers, such as styrene. PA1 1. Polymerization initiators such as t-butyl hydroperoxide, t-butyl perbenzoate, benzoyl peroxide, t-butyl peroctoate, methyl ethyl ketone peroxide, and others know to the art. The polymerization initiator is employed in a catalytically effective amount, such as from about 0.3 to about 2 to 3 weight percent, based on the weight of the polyester plus monomer plus low profile additive; PA1 2. Fillers such as clay, hydrate alumina silica, calcium carbonate and others known to the art; PA1 3. Reinforcing fillers such as glass fibers or fabrics, carbon fibers and fabrics, aramide fibers and fabrics, asbestos fibers or fabrics, polypropylene, acrylonitrile/vinyl chloride copolymers, PAN fibers and fabrics; PA1 4. Mold release agents or lubricants, such as zinc stearate, calcium stearate, calcium stearate, and others known to the art; and PA1 5. Rubbers or elastomers such as: PA1 1. Instron tensile testing machine; 10,000 pound cell. Universal Testing Machine Jaws. PA1 2. Instron oven with temperature control for 300.degree. F. PA1 3. Metal mounts for bonding to specimens with diameters at bonding area of 1.59 inches (2 square inch area). Two (2) mounts required per specimen, each pair numbered. Mounts threaded for attachment to Universal Testing Machine Jaws. PA1 4. Alignment fixture for holding metal mounts and specimen during oven curing of the bond.
an unsaturated polyester resin, and PA2 an ethylenically unsaturated monomer that is a solvent for the unsaturated polyester resin. PA2 a base resin system, and PA2 a thermoplastic low profile additive. PA2 a. homopolymers or copolymers of conjugated dienes have a weight average molecular weight of 30,000 to 400,000 or higher as described in U.S. Pat. No. 4,020,036. The conjugated dienes contain from 4-12 carbon atoms per molecule such as 1,3-butadiene, isoprene, and the like; PA2 b. epihalohydrin monomer(s), or a copolymer of an epihalohydrin monomer(s) with an oxide monomer(s) having a number average molecular weight (Mn) which varies from about 800 to about 50,000 as described in U.S. Pat. No. 4,101,604; PA2 c. chloroprene polymers including homopolymers of chloroprene and copolymers of chloroprene with sulfur and/or with at least one copolymerizable organic monomer wherein chloroprene constitutes at least 50 weight percent of the organic monomer make-up of the copolymer as described in U.S. Pat. No. 4,161,471; PA2 d. hydrocarbon polymers including ethylene/propylene dipolymers and copolymers of ethylene/propylene and at least one nonconjugated diene, such as ethylene/propylene/hexadiene terpolymers and ethylene/propylene/1,4-hexadiene/norbornadiene, as described in U.S. Pat. No. 4,161,471; PA2 e. conjugated diene butyl elastomers, such as copolymers consisting of from 85 to 99.5% by weight of a C.sub.4 -C.sub.7 is olefin having 4 to 14 carbon atoms, copolymers of isobutylene and isoprene where a major portion of the isoprene units combined therein have conjugated diene unsaturation as described in U.S. Pat. No. 4,160,759.